The Synthesis And Application Of Aqueous Polyurethane Adhesives Used In Pigment Dyeing

Polyacrylate adhesive is mostly used in pigment dyeing and printing as a result of its good performance in the application, howere, there is the release of formaldehyde and other environmental issues. The aim of this paper is to synthesize an ecofriendly aqueous polyester-based polyurethane adhesive by using hydroxyethyl ethylene diamine (AEEA) as the small chain extender, which has good adhesion properties and color fastness on cotton fabrics and cotton yarn in pigment dyeing.This paper mainly consists of two parts, the study of synthesis and properties of aqueous polyurethane adhesives, and the application of aqueous polyurethane adhesives in pigment dyeing.In this research, a series of aqueous polyurethane dispersions were synthesized based on the polyester polyol, isopHorone diisocyanate (IPDI),dimethylol propionic acid (DMPA) and small chain extender by prepolymer method. Discuss the reaction temperature, reaction time and catalyst to optimize the synthesis conditions of prepolymer:conditions in the absence of catalyst, the prepolymer temperature was 80℃for 2.5h, cooled down to 65℃, added DMPA and acetone solvent, then heated to 85℃for 2.5h.In the study of synthesis of aqueous polyurethane, the effect of the ratio of NCO/OH, the content of DMPA, solvent, degree of neutralization, small chain extender, and the solid content of polyols on the properties of emulsions and films were discussed. The chemical structure of films were characterized by FI-IR infrared spectrometer to determine the stable polyurethane dispersions. The glass transition temperature and thermal decomposition temperature of films were evaluated by thermal analysis. The particle size and viscosity of emulsions were measured by laser particle size analyzer and rotating viscometer, and use the centrifuge to test the stability of emulsions. In addition, the mechanical properties and water resistance testing were also carried out on films. The results showed that aqueous polyurethane had the best overall performance, including of small particle size and medium viscosity of the emulsion, good mechanical properties and water resistance of the films, which based on poly (1,4-butanediol adipate) (PBA), NCO/OH ratio R= 2.5,6% was the optimum dosage of DMPA, about 30% was the amount of acetone as a solvent, 100% neutralization degree, N-(2-hydroxyethyl) ethylenediamine (AEEA) as the small molecule chain extender.The effect of the amount of pigment and adhesive, the type of penetrant, fixing methods, curing temperature on the K/S value and washing & rubbing fastness properties were mainly discussed in the research of application of aqueous polyurethane on cotton fabrics and cotton yarn in pigment dyeing. Considering the cost and dyeing results, the optimum conditions were that the amount of pigment 30g/L, the amount of adhesive 30g/L, the amount of peregal O 5g/L, curing at 150℃for 3min after padding and pre-drying, then rinsing and drying. Compare WPU to polyacrylate adhesive M-HF, the results showed that PBA-based WPU achieved to the desired experimental results, which used N-(2-hydroxyethyl) ethylenediamine as the small molecule chain extender.